5396 fix longjmp clobbering errors

illumos/illumos-gate@67a4bb8f9ad4c49e9aa9e21e2114a7c093c3a73a

Reviewed by: Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
Reviewed by: Igor Kozhukhov <ikozhukhov@gmail.com>
Approved by: Richard Lowe <richlowe@richlowe.net>
Author: Gary Mills <gary_mills@fastmail.fm>